Peel the onions under running water to prevent watering eyes.

Cut the onions into 1/4-inch slices and separate them into rings.

Heat vegetable oil (at least 1-inch deep) in a deep fryer or 3-quart saucepan to 375°F.

In a bowl, beat the egg.

Add milk, flour, and salt to the beaten egg.

Mix until the batter is smooth.

Dip each onion ring into the batter, allowing excess batter to drip back into the bowl.

Fry a few rings at a time in the hot oil, turning once, until golden brown (about 2 minutes).

Drain the fried onion rings on a paper towel-lined plate.

Serve immediately.